how do i get the old and the new post title when it was changed

Hey,

i am struggling at the moment with a little problem.

I want to compare the old and the new title of a updated post.
But how do i get the data?

i tried it in the functions.php with the pre_update_post hook to get the old title and the save_title hook to get the new title of the post.
After that i would like to compare this two values and if they are the same, don’t do nothing, but when they are different, do a certain action:

[Code moderated as per the Forum Rules. Please use the pastebin]

In my blog every item of my custom post type “aktive” creates a term in the category-taxonomy. When i edit the name of an “aktive”-item i want that the term which was created at the first time, also gets its name changed accordingly. But it doesnt do with the code above.

Thankful for any advice.
em_vau